Sonoma Water
Released by: Water Agency
For Immediate Release

Sonoma Water Files Petition to Maximize Reservoir Storage

Santa Rosa, CA  –  November 22, 2021  –  The Sonoma County Water Agency (Sonoma Water) has filed a petition with the State Water Resources Control Board to ensure that its already depleted reservoirs are not further affected by reduced flows from the Potter Valley Project due to a mechanical failure at the PG&E hydroelectric facility. 

The Potter Valley Project (PVP) diverts water from the Eel River through a tunnel and hydropower facility operated by PG&E. The water flows through the Potter Valley and into Lake Mendocino. Typically, the water supply condition, which establishes minimum instream flows in the Russian River, is determined by inflow into Lake Pillsbury, located upstream of the Potter Valley Project. But because the water imported from the Eel River into the Russian River will be greatly diminished due to the hydropower plant failure, there will be little to no correlation between cumulative inflow into Lake Pillsbury and the hydrologic conditions in the Russian River watershed. 

Sonoma Water has filed a Temporary Urgency Change Petition (TUCP) requesting that the water supply condition and associated minimum instream flow requirements be determined based on storage thresholds at Lake Mendocino.  The same storage thresholds were requested by Sonoma Water in prior TUCPs filed in December 2013 and January 2021, which the State Water Board approved in orders issued on December 31, 2013 and February 4, 2021, respectively. Lake Mendocino and Lake Sonoma remain at or near their lowest levels for this time of year since filling in 1959 and 1986, respectively.  This makes it even more critical that the water supply condition and corresponding minimum instream flows in the Russian River be determined by a hydrologic index representative of the Russian River watershed. 

“This is a common-sense approach to a complex situation, which is exacerbated by the ongoing drought,” said Sonoma County Supervisor and Sonoma Water Board of Directors Chair Lynda Hopkins. “We need to do everything we can to maintain water in our reservoirs for the health and safety of our communities and environment. I’m hopeful the State Water Board will support our efforts to conserve every drop of water and get through this drought together.” 

If the TUCP is approved, the water supply condition would remain “critical” through the December 31, 2021.  On January 1, 2022 the water supply condition will be re-evaluated based on storage in Lake Mendocino and monthly thereafter until June 1, 2022 when the water supply condition will be set until the end of the year.

PG&E officials have indicated that it is unlikely the company will repair the facility given the likelihood that it may surrender its license to continue operating the PVP.

A copy of the November 2021 TUCP is available at:


Contact Information

Barry Dugan  

Principal Programs Specialist
Community and Government Affairs

Sonoma Water

Contact us by Phone
404 Aviation Boulevard
Santa Rosa, CA 95403
38.51193, -122.7835